/*	$OpenBSD: csplit.c,v 1.10 2021/07/08 00:38:42 millert Exp $	*/
/*	$FreeBSD: src/usr.bin/csplit/csplit.c,v 1.9 2004/03/22 11:15:03 tjr Exp
 * $	*/

/*-
 * Copyright (c) 2002 Tim J. Robbins.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * csplit -- split files based on context
 *
 * This utility splits its input into numbered output files by line number
 * or by a regular expression. Regular expression matches have an optional
 * offset with them, allowing the split to occur a specified number of
 * lines before or after the match.
 *
 * To handle negative offsets, we stop reading when the match occurs and
 * store the offset that the file should have been split at, then use
 * this output file as input until all the "overflowed" lines have been read.
 * The file is then closed and truncated to the correct length.
 *
 * We assume that the output files can be seeked upon (ie. they cannot be
 * symlinks to named pipes or character devices), but make no such
 * assumption about the input.
 */

#include "compat.h"

#include <sys/types.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <regex.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void cleanup(void);
void do_lineno(const char *);
void do_rexp(const char *);
char *get_line(void);
void handlesig(int);
FILE *newfile(void);
void toomuch(FILE *, long);
static void usage(void);

/*
 * Command line options
 */
const char *prefix; /* File name prefix */
long sufflen;       /* Number of decimal digits for suffix */
int sflag;          /* Suppress output of file names */
int kflag;          /* Keep output if error occurs */

/*
 * Other miscellaneous globals (XXX too many)
 */
long lineno;             /* Current line number in input file */
long reps;               /* Number of repetitions for this pattern */
long nfiles;             /* Number of files output so far */
long maxfiles;           /* Maximum number of files we can create */
char currfile[PATH_MAX]; /* Current output file */
const char *infn;        /* Name of the input file */
FILE *infile;            /* Input file handle */
FILE *overfile;          /* Overflow file for toomuch() */
off_t truncofs;          /* Offset this file should be truncated at */
int doclean;             /* Should cleanup() remove output? */

int main(int argc, char *argv[]) {
  setprogname(argv[0]);
  struct sigaction sa;
  long i;
  int ch;
  const char *expr;
  char *ep, *p;
  FILE *ofp;

  kflag = sflag = 0;
  prefix = "xx";
  sufflen = 2;
  while ((ch = getopt(argc, argv, "f:kn:s")) != -1) {
    switch (ch) {
    case 'f':
      prefix = optarg;
      break;
    case 'k':
      kflag = 1;
      break;
    case 'n':
      errno = 0;
      sufflen = strtol(optarg, &ep, 10);
      if (sufflen <= 0 || *ep != '\0' || errno != 0)
        errx(1, "%s: bad suffix length", optarg);
      break;
    case 's':
      sflag = 1;
      break;
    default:
      usage();
    }
  }

  if (sufflen + strlen(prefix) >= PATH_MAX)
    errx(1, "name too long");

  argc -= optind;
  argv += optind;

  if ((infn = *argv++) == NULL)
    usage();
  if (strcmp(infn, "-") == 0) {
    infile = stdin;
    infn = "stdin";
  } else if ((infile = fopen(infn, "r")) == NULL)
    err(1, "%s", infn);

  if (!kflag) {
    doclean = 1;
    atexit(cleanup);
    sa.sa_flags = 0;
    sa.sa_handler = handlesig;
    sigemptyset(&sa.sa_mask);
    sigaddset(&sa.sa_mask, SIGHUP);
    sigaddset(&sa.sa_mask, SIGINT);
    sigaddset(&sa.sa_mask, SIGTERM);
    sigaction(SIGHUP, &sa, NULL);
    sigaction(SIGINT, &sa, NULL);
    sigaction(SIGTERM, &sa, NULL);
  }

  lineno = 0;
  nfiles = 0;
  truncofs = 0;
  overfile = NULL;

  /* Ensure 10^sufflen < LONG_MAX. */
  for (maxfiles = 1, i = 0; i < sufflen; i++) {
    if (maxfiles > LONG_MAX / 10)
      errx(1, "%ld: suffix too long (limit %ld)", sufflen, i);
    maxfiles *= 10;
  }

  /* Create files based on supplied patterns. */
  while (nfiles < maxfiles - 1 && (expr = *argv++) != NULL) {
    /* Look ahead & see if this pattern has any repetitions. */
    if (*argv != NULL && **argv == '{') {
      errno = 0;
      reps = strtol(*argv + 1, &ep, 10);
      if (reps < 0 || *ep != '}' || errno != 0)
        errx(1, "%s: bad repetition count", *argv + 1);
      argv++;
    } else
      reps = 0;

    if (*expr == '/' || *expr == '%') {
      do {
        do_rexp(expr);
      } while (reps-- != 0 && nfiles < maxfiles - 1);
    } else if (isdigit((unsigned char)*expr))
      do_lineno(expr);
    else
      errx(1, "%s: unrecognised pattern", expr);
  }

  /* Copy the rest into a new file. */
  if (!feof(infile)) {
    ofp = newfile();
    while ((p = get_line()) != NULL && fputs(p, ofp) == 0)
      ;
    if (!sflag)
      printf("%jd\n", (intmax_t)ftello(ofp));
    if (fclose(ofp) != 0)
      err(1, "%s", currfile);
  }

  toomuch(NULL, 0);
  doclean = 0;

  return (0);
}

static void usage(void) {
  extern const char *__progname;

  fprintf(stderr, "usage: %s [-ks] [-f prefix] [-n number] file args ...\n",
          __progname);
  exit(1);
}

/* ARGSUSED */
void handlesig(int sig) {
  const char msg[] = "csplit: caught signal, cleaning up\n";

  write(STDERR_FILENO, msg, sizeof(msg) - 1);
  cleanup();
  _exit(2);
}

/* Create a new output file. */
FILE *newfile(void) {
  FILE *fp;

  if ((size_t)snprintf(currfile, sizeof(currfile), "%s%0*ld", prefix,
                       (int)sufflen, nfiles) >= sizeof(currfile)) {
    errno = ENAMETOOLONG;
    err(1, "%s", currfile);
  }
  if ((fp = fopen(currfile, "w+")) == NULL)
    err(1, "%s", currfile);
  nfiles++;

  return (fp);
}

/* Remove partial output, called before exiting. */
void cleanup(void) {
  char fnbuf[PATH_MAX];
  long i;

  if (!doclean)
    return;

  /*
   * NOTE: One cannot portably assume to be able to call snprintf() from
   * inside a signal handler.  It is, however, safe to do on OpenBSD.
   */
  for (i = 0; i < nfiles; i++) {
    snprintf(fnbuf, sizeof(fnbuf), "%s%0*ld", prefix, (int)sufflen, i);
    unlink(fnbuf);
  }
}

/* Read a line from the input into a static buffer. */
char *get_line(void) {
  static char lbuf[LINE_MAX];
  FILE *src;

  src = overfile != NULL ? overfile : infile;

again:
  if (fgets(lbuf, sizeof(lbuf), src) == NULL) {
    if (src == overfile) {
      src = infile;
      goto again;
    }
    return (NULL);
  }
  if (ferror(src))
    err(1, "%s", infn);
  lineno++;

  return (lbuf);
}

/* Conceptually rewind the input (as obtained by get_line()) back `n' lines. */
void toomuch(FILE *ofp, long n) {
  char buf[BUFSIZ];
  size_t i, nread;

  if (overfile != NULL) {
    /*
     * Truncate the previous file we overflowed into back to
     * the correct length, close it.
     */
    if (fflush(overfile) != 0)
      err(1, "overflow");
    if (ftruncate(fileno(overfile), truncofs) != 0)
      err(1, "overflow");
    if (fclose(overfile) != 0)
      err(1, "overflow");
    overfile = NULL;
  }

  if (n == 0)
    /* Just tidying up */
    return;

  lineno -= n;

  /*
   * Wind the overflow file backwards to `n' lines before the
   * current one.
   */
  do {
    if (ftello(ofp) < (off_t)sizeof(buf))
      rewind(ofp);
    else
      fseeko(ofp, -(off_t)sizeof(buf), SEEK_CUR);
    if (ferror(ofp))
      errx(1, "%s: can't seek", currfile);
    if ((nread = fread(buf, 1, sizeof(buf), ofp)) == 0)
      errx(1, "can't read overflowed output");
    if (fseeko(ofp, -(off_t)nread, SEEK_CUR) != 0)
      err(1, "%s", currfile);
    for (i = 1; i <= nread; i++)
      if (buf[nread - i] == '\n' && n-- == 0)
        break;
    if (ftello(ofp) == 0)
      break;
  } while (n > 0);
  if (fseeko(ofp, (off_t)(nread - i + 1), SEEK_CUR) != 0)
    err(1, "%s", currfile);

  /*
   * get_line() will read from here. Next call will truncate to
   * truncofs in this file.
   */
  overfile = ofp;
  truncofs = ftello(overfile);
}

/* Handle splits for /regexp/ and %regexp% patterns. */
void do_rexp(const char *expr) {
  regex_t cre;
  intmax_t nwritten;
  long ofs;
  int first;
  char *ecopy, *ep, *p, *pofs, *re;
  FILE *ofp;

  if ((ecopy = strdup(expr)) == NULL)
    err(1, "strdup");

  re = ecopy + 1;
  if ((pofs = strrchr(ecopy, *expr)) == NULL || pofs[-1] == '\\')
    errx(1, "%s: missing trailing %c", expr, *expr);
  *pofs++ = '\0';

  if (*pofs != '\0') {
    errno = 0;
    ofs = strtol(pofs, &ep, 10);
    if (*ep != '\0' || errno != 0)
      errx(1, "%s: bad offset", pofs);
  } else
    ofs = 0;

  if (regcomp(&cre, re, REG_NOSUB) != 0)
    errx(1, "%s: bad regular expression", re);

  if (*expr == '/')
    /* /regexp/: Save results to a file. */
    ofp = newfile();
  else {
    /* %regexp%: Make a temporary file for overflow. */
    if ((ofp = tmpfile()) == NULL)
      err(1, "tmpfile");
  }

  /* Read and output lines until we get a match. */
  first = 1;
  while ((p = get_line()) != NULL) {
    if (fputs(p, ofp) != 0)
      break;
    if (!first && regexec(&cre, p, 0, NULL, 0) == 0)
      break;
    first = 0;
  }

  if (p == NULL) {
    toomuch(NULL, 0);
    errx(1, "%s: no match", re);
  }

  if (ofs <= 0) {
    /*
     * Negative (or zero) offset: throw back any lines we should
     * not have read yet.
     */
    if (p != NULL) {
      toomuch(ofp, -ofs + 1);
      nwritten = (intmax_t)truncofs;
    } else
      nwritten = (intmax_t)ftello(ofp);
  } else {
    /*
     * Positive offset: copy the requested number of lines
     * after the match.
     */
    while (--ofs > 0 && (p = get_line()) != NULL)
      fputs(p, ofp);
    toomuch(NULL, 0);
    nwritten = (intmax_t)ftello(ofp);
    if (fclose(ofp) != 0)
      err(1, "%s", currfile);
  }

  if (!sflag && *expr == '/')
    printf("%jd\n", nwritten);

  regfree(&cre);
  free(ecopy);
}

/* Handle splits based on line number. */
void do_lineno(const char *expr) {
  long lastline, tgtline;
  char *ep, *p;
  FILE *ofp;

  errno = 0;
  tgtline = strtol(expr, &ep, 10);
  if (tgtline <= 0 || errno != 0 || *ep != '\0')
    errx(1, "%s: bad line number", expr);
  lastline = tgtline;
  if (lastline <= lineno)
    errx(1, "%s: can't go backwards", expr);

  while (nfiles < maxfiles - 1) {
    ofp = newfile();
    while (lineno + 1 != lastline) {
      if ((p = get_line()) == NULL)
        errx(1, "%ld: out of range", lastline);
      if (fputs(p, ofp) != 0)
        break;
    }
    if (!sflag)
      printf("%jd\n", (intmax_t)ftello(ofp));
    if (fclose(ofp) != 0)
      err(1, "%s", currfile);
    if (reps-- == 0)
      break;
    lastline += tgtline;
  }
}
